// dp[i][j]表示（i,j）的所有路径数量
// dp[i][j] = dp[i-1][j] + dp[i][j-1] if dp[i][j] != block
// dp[i][j] = 0 if dp[i][j] == block
class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();
        vector<vector<int>> dp(m, vector<int>(n));
        for (int i = 0; i < m; ++i) {
            if (obstacleGrid[i][0]) {
                break;
            }
            dp[i][0] = 1;
        }
        for (int i = 0; i < n; ++i) {
            if (obstacleGrid[0][i]) {
                break;
            }
            dp[0][i] = 1;
        }
        for (int i = 1; i < m; ++i) {
            for (int j = 1; j < n; ++j) {
                dp[i][j] = obstacleGrid[i][j] ? 0 : dp[i - 1][j] + dp[i][j - 1];
            }
        }
        return dp[m - 1][n - 1];
    }
};